Materials samples and biomedical samples frequently have high contrast ratios. These high contrast ratios cannot be covered by a single measurement, for example, with the Zeiss LSM 700. For this purpose, there are HDR (High Dynamic Range) methods in which the measurement result is composed of a number of individual measurements with different illumination intensities or detector sensitivities (PMT gain). However, the measurements are carried out consecutively, which leads to the following problems.
In the field of materials (topography measurement):    Long measuring times. Since scanning must be at least doubled, the measuring time is at least doubled.    The risk that not exactly the same measuring points will be scanned in the individual measurements, e.g., due to vibrations and scanners which do not run in an exact manner.    Calculated height values which are based on evaluation of a PSF with a low intensity generally exhibit noisier performance.
In the biomedical field:    Long measuring times. Since scanning must be at least doubled, the measuring time is at least doubled.    The risk that not exactly the same measuring points will be scanned in the individual measurements, e.g., due to vibrations and scanners which do not run in an exact manner.    The sample is stressed to a greater extent due to the doubled scanning, which can lead to a bleaching of the sample.    When viewing living cells, changes may occur in the cells, i.e., the sample, between individual measurements; that is, combining the observation of living cells with HDR is useful only to a limited extent with present-day methods.    In current methods, a number of measurements are carried out consecutively and then calculated. The individual measurements are sometimes combined to form a measurement sequence which appears outwardly as an individual measurement. Optical elements such as mirror arrays or sensor parameters are then changed between the partial measurements.    For HDR cameras, there are special camera chips which can acquire a greater dynamic range. However, they are not suitable as a substitute for the photomultiplier tubes (“PMTs”).
In another field, that of ophthalmology (DE102007046210A1), a fundus image with expanded dynamics is generated by means of a beamsplitter with an asymmetrical splitting ratio and a plurality of image sensors.